Engine not running happy upon first start up
I have a small block 350 4 bolt main, that we changed all the seals on and put a new Comp Cams cam and lifters. It also got a new cap, rotor, and wires. the old edelbrock preformer intake, Edelbrock 1406 600 4 barrel Carb went back on. The truck also is getting a whole new painless wiring harness
On first attempt to start up it didnt want to fire i removed the distributor and made sure it was inserted correctly with the #1 cylinder at TDC rotor pointing at the #1 cylinder, #1 wire on that post and double checked the wires were on in the right order. After that it fired right up, tried bringing up the rpm to 2k for the break in and i am getting some LOUD backfiring through the carb at about 2K rpm. I shut it down and reset the idle mixture screws to 1.5 turns out each and made sure the air filter was on tight. It started happier but still backfires through the carb at 2k rpm. Also after turning off the key one time it kept running, for a few seconds.
I would like to get some suggestions from you guys on what else to check/inspect/additional info you need. This is my first cam swap and want to get this thing broken in correctly. I'm not trying to tune for performance or anything right now, just want to be able to have it running at 2k rpm so i can break in the new cam